The Raptor 250 was Yamaha's intended replacement for the Blaster, even though the little Raptor is physically smaller and than the older Blaster. It is totally redesigned as well. Unlike in the Blaster, the little air cooled, SOHC 250 4-stroke engine in the Raptor doesn't have a lot of mod potential. Sure, you can add an exhaust, open up the airbox, rejet, and add a cam, but apart from that, there's no magic power gains to be had.
Stock for stock, they say the Rappy 250 and Blaster will run neck-in-neck in a race. See Youtube for proof. But take both bikes and add a pipe, jets, and airbox mods and Im pretty sure the Blaster would win, rider skill/weight equal of course. A ported Blaster will blow the little Raptor away. In fact, my ported Blaster will give just about any Raptor a run for its money, except for the 700 of course. I beat a stock 660 Rappy in the 300' last year at Busco. Sure, the Raptor rider was a 300lb novice on a stock bike, but a win's a win!! Lol.
Back on subject, the Raptor 350 has no relationship (besides being the same brand) to the Blaster. It is instead a revamped version of the venerable Warrior 350. Except for cosmetics, lights, and an exhaust header redesign on the later Raptor 350, both quads are virtually identical underneath. I used to own a Warrior and it was...limited...on what could be done performance-wise. It was heavy and slow, but still jumped reasonably well and was fun on the trails. Id still rather have my Blaster, though. The Warrior/Raptor 350's SOHC, 2-valve engine has its origins in the Moto-4 machines of the '80's, and it behaves as such. Reliable as an anvil but mild-mannered no matter how many aftermarket parts you throw at it. I had a Supertrapp pipe, K&N air filter, open airbox, and Edelbrock carb on my old Warrior and I was still just putting more and more lipstick on my pig.